In the parent application, an assembly and method are provided which facilitate the easy and inexpensive loading and unloading of overseas (long distance) transport containers. Utilizing fingers having air bearings disposed along the bottoms thereof, in a particular manner, it is possible to easily load and unload standard 20 and 40 foot containers, with virtually any goods that are mountable on pallets within the containers. Since sometimes the loading dock, or other deck surface which the fingers traverse during the loading and/or unloading operation, is rough and uneven, it is desirable to place sheet material, such as flexible plastic sheet material, over the deck surface in order to smooth out the unevenness and facilitate the movement of the air bearings thereover.
According to the present invention, an automated system and method are provided for disposing sheet material over the deck surface to be traversed during loading and unloading of containers, so as to make such loading and unloading as trouble free as possible. While the invention is particularly described with respect to assemblies and methods for loading and unloading transport containers, the invention also has applicability to other situations in which it is desirable to dispense, and then retract, flexible sheet material.
According to one aspect of the present invention, an assembly is provided for facilitating the movement of a heavy load into or out of an overseas transport container. The assembly includes at least one finger having a plurality of air bearings disposed along the bottom thereof, the air bearings connected to a source of air under pressure associated with the finger. The height of the finger is such that it may be inserted underneath a pallet to effect lifting of the pallet. A coiled supply of sheet material capable of providing a smooth surface for the air bearings is preferably mounted on a front end of the finger. Means are provided for supplying a constant tension to the supply of sheet material, preferably an air driven motor mounted to the front end of the finger and connected to it by gears or the like for applying a tension of about 10 lbs. per square inch to the sheet material. An engaging means for engaging a free end of the sheet material is preferably mounted at a predetermined point along the deck surface. In this way the supply of sheet material and sheet material engaging means are mounted so that as the finger moves over the deck surface the engaging means automatically engages the free end of the sheet material and holds it stationary with respect to the deck while the sheet is dispensed underneath the finger and provides a smooth surface over which the air bearings move. The sheet material engaging means may comprise a hook or a magnet mounted in a recess in the deck surface, and the free end of the sheet material may contain a metal bar around which the sheet material is wrapped.
According to another aspect of the present invention there is provided a method of facilitating movement of a load over a deck surface, utilizing at least one finger having air bearings disposed along the bottom thereof, and plastic sheet material adapted to be disposed on the deck surface below the air bearings so as to smooth the deck surface and facilitate movement of the air bearings, and load carried thereby, thereover, the method comprising the steps of: (a) Automatically dispensing the sheet material so that as the finger moves over the deck surface the sheet material will be provided between the air bearings and the deck surface over a significant portion of the length of travel thereof. And, (b) automatically taking up the sheet material as the finger moves in a reverse direction with respect to the deck. Preferably steps (a) and (b) are practiced by: mounting a coil of sheet material to a front end of the finger; applying a constant tension to the sheet material; and engaging a free end of the sheet material to hold it stationary with respect to the deck while the finger moves over the deck.
According to another aspect of the present invention there is provided, in general, apparatus for the automatic dispensing of sheet material comprising: A frame. A shaft mounted for rotation with respect to the frame, the shaft having sheet material coiled therearound, the sheet material including a free end having an engageable means associated therewith. Means mounted on the frame for supplying a force to the shaft so that constant tension is applied to the sheet material as it is dispensed from the shaft; and means for engaging the engageable means at the free end of the sheet material and to hold the free end stationary while the frame moves with respect to the engaging means, so that the sheet material is dispensed below the frame.
It is the primary object of the present invention to provide the automatic dispensing of sheet material, preferably to facilitate the movement of a finger with air bearings, supporting a load, over a surface on which the sheet material is dispensed. This and other objects of the present invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.